by Kevin Johnson, USA TODAY

by Kevin Johnson, USA TODAY

WASHINGTON - More than 600 suspected gang members have been arrested across the country after a month-long operation by federal authorities targeting the fast-growing Sureños group, according to a report issued Thursday by the Department of Homeland Security.

Of the 638 arrests related to the department's Project Southbound, 525 were charged with criminal offenses, and 113 were swept up on immigration-related violations.

In addition to the arrests, authorities seized 54 firearms, 13 pounds of methamphetamine, 83 pounds of marijuana, 10 vehicles and $166,000 in cash.

The Sureños originated in Southern California and have hundreds of affiliate groups across the USA, according to the National Gang Intelligence Center's 2011 National Gang Threat Assessment.

U.S. Immigration and Customs Enforcement Principal Deputy Assistant Secretary Thomas Winkowski said the gang has more than 30,000 members in the USA, and "its numbers are growing.'' The Sureños largely operate in close proximity to the border, and its members have been linked to murder, extortion, drug trafficking, human smuggling and prostitution.

Seven of the arrestees were accused of murder and five of sexual assault.